轉貼自teched講師: 牛可
基本概念:
第一層 服務主密鑰
備份服務主密鑰
backup service master key to file='c:/smk.bak'
encryption by password='P@ssw0rd'
restore service master key from file='c:/smk.bak'
decryption by password='P@ssw0rd'
第二層 數據庫主密鑰
1)必須先在該數據庫上創建數據庫主密鑰才能使用
create master key encryption by password='P@ssw0rd'
2)使用數據庫主密鑰
－如果數據庫主密鑰使用服務密鑰進行保護，則在使用時會自動打開
opren master key decryption by password='P@ssw0rd'
3)查看數據庫主密鑰狀態
sys.symmetric_keys
4)備份數據庫主密鑰
backup master key to file='c:/smk.bak'
encryption by password='P@ssw0rd'
restore master key from file='c:/smk.bak'
decryption by password='P@ssw0rd'
數字證書
創建自簽名
create certificate cert_myCert
encryption by password='P@ssw0rd'
with subject='Self Signed Cert',
start_date='1/31/2006'
expiry_date='1/31/2008'
非對稱密鑰
創建新的密鑰對
create asymmetric key asy_Key1
with algorithm=RSA_2048
encryption by password='P@ssw0rd'
對稱密鑰
創建新的密鑰對
create symmetric key SymKeyMarketing3
with algorithm=AES_2048
encryption by certificate asy_Key1
使用對稱密鑰
使用前必須打開
open symmetric SymKeyMarketing3
decryption by certificate asy_Key1
sys.open_keys
數據列加密
－使用對稱密鑰加密大量的列數據
－考慮使用證書，非對稱密鑰保護對稱密鑰
防止繞過加密數據列的攻擊－使用驗證器
注:
在加密列上的索引將變得無效
加密數據列的長度增長，建議使用varbinary（max）數據類型
修改已有的dml語句以支持加密的數據列
-----***********示例1 瞭解數據庫加密體系結構*****-----
--************(1) 服務主密鑰
--準備工作
--創建測試數據庫TestDB
--1)備份服務主密鑰
backup service master key to file='g:/smk.bak'
encryption by password='p@ssw0rd'
--2)生成新的主密鑰
Alter service master key regenerate
--3)從備份文件還原服務主密鑰
Restore service master key from file= file='g:/smk.bak'
encryption by password='p@ssw0rd'
--*************(2) 數據庫主密鑰
--1)爲數據庫創建數據庫主密鑰
create master key encryption by password='p@ssw0rd'
go
--2)查看數據庫加密狀態
select [name],is_master_key_encrypted_by_server
from sys.databases where name='TestDB'
--3)查看數據庫主密鑰的信息
select * from sys.symmetric_keys
--4)備份數據庫主密鑰
backup master key
to file='g:/testdbkey.bak'
encryption by password='p@ssw0rd'
--5)刪除服務主密鑰對數據庫主密鑰的保護
--創建非對稱密鑰成功,自動使用服務主密鑰解密並使用該數據庫主密鑰
create asymmetric key asy_Testkey1 with algorithm=RSA_1024
go
--刪除服務主密鑰對數據庫主密鑰的保護
alter master key
drop encryption by service master key
go
--查看數據庫加密狀態
select [name],is_master_key_encrypted_by_server
from sys.databases where name='TestDB'
--創建非對稱密鑰失敗,因爲數據庫主密鑰未打開
create asymmetric key asy_Testkey2 with algorithm=RSA_1024
go
--打開數據庫主密鑰
open master key decryption by password='p@ssw0rd'
select * from sys.openkeys
go
--創建非對稱密鑰成功
create asymmetric key asy_Testkey2 with algorithm=RSA_1024
go
--恢復服務主密鑰對數據庫主密鑰的保護
alter master key
add encryption by service master key
close master key
go
--*****(3)證書
--1)創建自簽名證書
create certificate cert_Testcert
encryption by password='p@ssw0rd'
with subject='TestCert1',
start_date='1/31/2006',
expiry_date='1/31/2008'
go
select * from sys.certificates
--2)從文件導入證書
Create certificate cert_TestCert2
From file=’g:/MSCert.cer’
Go
-- 3)備份導出證書和密鑰
backup certificate cert_Testcert
to file='g:/Testcert.cer'
with private key
(decryption by password='p@ssw0rd',
file='g:/TestCert_pvt',--私密鑰
encryption by password='p@ssw0rd' )
go
--4)使用證書加解密數據
--加密:使用證書的公鑰
declare @cleartext varbinary(200)
declare @cipher varbinary(200)
set @cleartext=convert( varbinary(200),'Test text string')
set @cipher=EncryptByCert(Cert_ID('cert_TestCert'),@cleartext)
select @cipher
--解密:使用證書的私鑰
select convert(varchar(200),DecryptByCert(Cert_ID('cert_TestCert'),@cipher,N'p@ssw0rd')) as [cleartext]
--5) 刪除證書私鑰
alter certificate cert_TestCert
remove private key
go
--加密成功
declare @cleartext varbinary(200)
declare @cipher varbinary(200)
set @cleartext=convert( varbinary(200),'Test text string')
set @cipher=EncryptByCert(Cert_ID('cert_TestCert'),@cleartext)
select @cipher
--解密失敗:因爲私鑰被刪除
select convert(varchar(200),DecryptByCert(Cert_ID('cert_TestCert'),@cipher,N'p@ssw0rd')) as [cleartext]
--***(4) 非對稱密鑰
--1)使用sn.exe生成非對稱密鑰,安裝vs2005後有sn.exe, 在命令行方式下執行
sn -k g:/asy_Test.key
--2)從文件創建非對稱密鑰
create asymmetric key asm_Test
from file='g:/asy_Test.key'
encryption by password='p@ssw0rd'
go
select * from sys.asymmetric_keys
--***********示例2 使用加密保護列數據
-----*****(1) 準備工作
--1) 創建示例表
create table empsalary
(EmpID int,
Title nvarchar(50),
Salary varbinary(500)
)
go
--2) 創建數據庫主密鑰
create master key encryption by password='p@ssw0rd'
go
--3) 創建用於加密的對稱密鑰
create symmetric key sym_Salary
with algorithm=AES_192
encryption by password='p@ssw0rd'
go
select * from sys.symmetric_keys where [name]='sym_Salary'
------****(2)加密列數據
--1)打開對稱密鑰
open symmetric key sym_Salary
decryption by password='p@ssw0rd'
go
select * from sys.openkeys
--2)向表中插入數據，並對salary列加密
insert into empsalary values (1,'CEO',EncryptByKey(KEY_GUID('sym_Salary'),'20000'))
insert into empsalary values (2,'Manager',EncryptByKey(KEY_GUID('sym_Salary'),'10000'))
insert into empsalary values (3,'DB Admin',EncryptByKey(KEY_GUID('sym_Salary'),'5000'))
--3)關閉打開的對稱密鑰
close symmetric key sym_Salary
go
select * from sys.openkeys
--4) 查看錶中的數據
select * from empsalary
--(3)解密並訪問被加密的數據列
--1)打開對稱密鑰
open symmetric key sym_Salary decryption by password='p@ssw0rd'
go
--2)使用對稱密鑰解密並訪問被加密的列
select empid,title,cast(DecryptByKey(Salary) as varchar(20)) as salary from empsalary
--3) 關閉對稱密鑰
close symmetric key sym_Salary
go
--(4)繞過加密數據的攻擊
--1)攻擊者使用其他數據行的加密數據替換某一行的數據
update empsalary
set salary=(select salary from empsalary where empid=1)
where empid=3
--2)查看被攻擊後解密的數據
open symmetric key sym_Salary decryption by password='p@ssw0rd'
select empid,title,cast(DecryptByKey(Salary) as varchar(20)) as salary from empsalary
close symmetric key sym_Salary
--(5)使用驗證器防止繞過加密數據的攻擊
--1)刪除前面添加的數據行
delete empsalary
--2)向表插入數據，並對salary列的數據使用驗證器進行加密
open symmetric key sym_Salary decryption by password='p@ssw0rd'
insert into empsalary values (1,'CEO',EncryptByKey(KEY_GUID('sym_Salary'),'20000',1,'1'))
insert into empsalary values (2,'Manager',EncryptByKey(KEY_GUID('sym_Salary'),'10000',1,'2'))
insert into empsalary values (3,'DB Admin',EncryptByKey(KEY_GUID('sym_Salary'),'5000',1,'3'))
--3)解密並訪問被加密的數據
select empid,title,cast(DecryptByKey(Salary,1,cast(empid as varchar(3))) as varchar(20)) as salary from empsalary
--4)用同樣的方法篡改數據
update empsalary
set salary=(select salary from empsalary where empid=1)
where empid=3
--5)被篡改後的加密了的數據列變成無效
select empid,title,cast(DecryptByKey(Salary,1,cast(empid as varchar(3))) as varchar(20)) as salary from empsalary
--***********示例3 使用數字證書籤署存儲過程
--*****(1)準備
--1)創建數據庫主密鑰
create master key encryption by password='p@ssw0rd'
--2)創建簽署存儲過程所需要的證書
create certificate cert_Product
with subject='Products Sign',
start_date='1/31/2006',
expiry_date='1/31/2008'
go
--3)創建SPDeveloper登錄帳戶和用戶，該用戶創建並訪問Products表的存儲過程
create login [SPDeveloper] with password='p@ssw0rd',default_database=[TestDB]
go
create user [SPDeveloper] for login SPDeveloper with default_schema=[SPDeveloper]
go
create schema products authorization SPDeveloper
go
exec sp_addrolemember @rolename='db_owner',@membername='SPDeveloper'
--4)以SPDeveloper的身份創建存儲過程products.usp_Products
execute as user='SPDeveloper'
go
create procedure products.usp_Products
as
select * from dbo.Products
go
revert
select user
--5)創建普通用戶jerry
create login [jerry] with password='p@ssw0rd',default_database=[TestDB]
go
create user [jerry] for login jerry
go
--*******(2)使用證書籤署存儲過程
--1)授予用戶jerry執行存儲過程的權限
grant execute on products.usp_Products to jerry
--2)以jerry的身份執行存儲過程失敗，因爲擁有權鏈的斷裂的
execute as user='jerry'
select user
go
execute products.usp_Products
go
revert
--3)使用證書在當前數據庫創建用戶ProductsReader,併爲該用戶賦予讀取products表的權限
create user ProductsReader for certificate cert_Products
go
grant select on products To ProductsReader
--4)使用證書籤署當前存儲過程
add signature to products.usp_Products by certificate cert_Products
--5)以jerry的身份重新執行存儲過程，成功
--因爲存儲過程將以ProductsReader的權限上下文執行
execute as user='jerry'
select user
go
execute products.usp_Products
go
revert